Method parse_interval_value

src/sql-parser/src/parser.rs:1199–1274

Parse an INTERVAL literal. Some syntactically valid intervals: - `INTERVAL '1' DAY` - `INTERVAL '1-1' YEAR TO MONTH` - `INTERVAL '1' SECOND` - `INTERVAL '1:1' MINUTE TO SECOND - `INTERVAL '1:1:1.1' HOUR TO SECOND (5)` - `INTERVAL '1.111' SECOND (2)`

(&mut self)

    ///   - `INTERVAL '1.111' SECOND (2)`
    ///
    fn parse_interval_value(&mut self) -> Result<IntervalValue, ParserError> {
        // The first token in an interval is a string literal which specifies
        // the duration of the interval.
        let value = self.parse_literal_string()?;

        // Determine the range of TimeUnits, whether explicit (`INTERVAL ... DAY TO MINUTE`) or
        // implicit (in which all date fields are eligible).
        let (precision_high, precision_low, fsec_max_precision) =
            match self.expect_one_of_keywords(&[
                YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, YEARS, MONTHS, DAYS, HOURS, MINUTES,
                SECONDS,
            ]) {
                Ok(d) => {
                    let d_pos = self.peek_prev_pos();
                    if self.parse_keyword(TO) {
                        let e = self.expect_one_of_keywords(&[
                            YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, YEARS, MONTHS, DAYS, HOURS,
                            MINUTES, SECONDS,
                        ])?;

                        let high: DateTimeField = d
                            .as_str()
                            .parse()
                            .map_err(|e| self.error(self.peek_prev_pos(), e))?;
                        let low: DateTimeField = e
                            .as_str()
                            .parse()
                            .map_err(|e| self.error(self.peek_prev_pos(), e))?;

                        // Check for invalid ranges, i.e. precision_high is the same
                        // as or a less significant DateTimeField than
                        // precision_low.
                        if high >= low {
                            return parser_err!(
                                self,
                                d_pos,
                                "Invalid field range in INTERVAL '{}' {} TO {}; the value in the \
                                 position of {} should be more significant than {}.",
                                value,
                                d,
                                e,
                                d,
                                e,
                            );
                        }

                        let fsec_max_precision = if low == DateTimeField::Second {
                            self.parse_optional_precision()?
                        } else {
                            None
                        };

                        (high, low, fsec_max_precision)
                    } else {
                        let low: DateTimeField = d
                            .as_str()
                            .parse()
                            .map_err(|e| self.error(self.peek_prev_pos(), e))?;